tag-watcher

Kubernetes CRD/operator that will scan remote docker repositories, match a subset of tags based on user input, and then reflect those images (with user-specificed changes) to another docker repository

Description

A personal kubebuilder project, the aim is to give cluster operators an easy way to add customizations to vendored OCI images. The advantage to using this method vs the standard Dockerfile is that for vendored images that tag via release version && release often, you can have a background process continueing providing your customized images on that same release schedule. As with most devops discussions, there are 100+ ways to solve this problem, but this one is mine :) My personal use comprises of k3d clusters running with local registries, the operator will pull from dockerhub (or whatever registry the vendor uses), then add some packages/tweaks, and push to the local k3d registry.

This project is very much still in development (TODO: remove this when the previous paragraph is fully possible)

Big TODOs

• Need a way to hit a docker socket inside the cluster, hoping to use DIND container, but need to do some research/testing
• Tests.... test test test
• Way to invoke the logic outside of the controller; ie some kind of CLI
• Report errors with the push to second registry
• Document deployment steps in README
• Helm Chart For Deployments (can kubebuilder do this automatically?)

Getting Started

You’ll need a Kubernetes cluster to run against. You can use KIND to get a local cluster for testing, or run against a remote cluster. Note: Your controller will automatically use the current context in your kubeconfig file (i.e. whatever cluster kubectl cluster-info shows).

Running on the cluster

1. Install Instances of Custom Resources:

kubectl apply -f config/samples/

2. Build and push your image to the location specified by IMG:

make docker-build docker-push IMG=<some-registry>/tag-watcher:tag

3. Deploy the controller to the cluster with the image specified by IMG:

make deploy IMG=<some-registry>/tag-watcher:tag

Uninstall CRDs

To delete the CRDs from the cluster:

make uninstall

Undeploy controller

UnDeploy the controller to the cluster:

make undeploy

Contributing

// TODO(user): Add detailed information on how you would like others to contribute to this project

How it works

This project aims to follow the Kubernetes Operator pattern

It uses Controllers which provides a reconcile function responsible for synchronizing resources untile the desired state is reached on the cluster

Test It Out

1. Install the CRDs into the cluster:

make install

2. Run your controller (this will run in the foreground, so switch to a new terminal if you want to leave it running):

make run

NOTE: You can also run this in one step by running: make install run

Modifying the API definitions

If you are editing the API definitions, generate the manifests such as CRs or CRDs using:

make manifests

NOTE: Run make --help for more information on all potential make targets

More information can be found via the Kubebuilder Documentation

License

Copyright 2023.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.